1. Field of the Invention
The present invention relates to a composition for forming a resist underlayer film, and a pattern-forming method.
2. Discussion of the Background
In manufacturing integrated circuit elements and the like, a pattern-forming method utilizing a multilayer resist process has been in widespread use to meet miniaturization of processing size. With respect to the multilayer resist process, in general, a composition for forming a resist underlayer film is applied on the upper side of a substrate to provide a resist underlayer film, and a resist composition is further applied on the upper side of resist underlayer film to provide a resist film. Then, a transfer of a mask pattern by way of irradiation with exposure light and a subsequent development yields a resist pattern. Subsequently, the resist pattern is transferred to the resist underlayer film by dry etching. Finally, the resist underlayer film pattern is transferred to the substrate by dry etching, whereby the substrate with a desired pattern can be obtained.
In general, materials having a high carbon content are used for the resist underlayer film provided directly on the substrate. Such a high carbon content leads to an increase of etching selectivity in the processing of the substrate, which enables more precise pattern transfer. Known compositions for forming such a resist underlayer film include: a composition that contains a thermosetting phenol novolak resin (see PCT International Publication No. 2009/072465); a composition that contains an acenaphthylene resin (see Japanese Unexamined Patent Application, Publication Nos. 2000-143937 and 2001-40293); and a composition that contains a calixarene (see Japanese Unexamined Patent Application, Publication No. 2008-116677), and these compositions can reportedly provide a resist underlayer film exhibiting superior etching resistance.
On the other hand, in these days, formation of a pattern on a substrate having a plurality of types of trenches, in particular, trenches differing from one another in terms of an aspect ratio has been executed more frequently.